Not reading all these pages, but my two cents.
No,
I think you're just expecting fine art where you shouldn't be.
I dont disagree with your complaints;
the villains are (usually) very lackluster, the comedy does sometimes undervalue the drama, and the uniformity of the production process does lend a kind of sameness to all the films (though given the shared continuity I consider that something of a good thing).
But these films aren't trying to be anything other than big, loud, bombastic summer blockbusters. They're not trying to have a deep exploration of the human condition or tell a story that'll make you think. You're supposed to just turn your mind off, enjoy the visual spectacle and laugh at the quippy one-liners. So for what they are, the MCU films do their job fairly well.
And as for the villains.....these actors only do so many films, and most of the time Marvel wants to use different villains for each movie, so there's no real need to keep them alive. The MCU is a long-running narrative like the comics yes, but unlike the comics the individual characters are only going to be around for so long so you're only going to get so much mileage out of their rogues galleries.
If that's not what you look for in movies, it makes sense that you're not a fan of the MCU. Its actually not what I look for in movies most of the time either, but I adjust my expectations for Marvel because I know what they're offering and it has worked really, really well for them and they're not going to change.
Maybe the Disney+ shows will be more to your liking. I'm sure they'll still have many of the problems you mention, but the extra air time might allow for some deeper character work, the humor might be more spread out and placed in more appropriate places, and I suspect at least a few of the villains will last beyond the finale. We know Zemo is coming back for Falcon-Winter Soldier, so there's one bad guy who survived his first movie, and Wandavision is tying into Dr. Strange 2 so I wouldn't be surprised if Nightmare turns out to have a role in the show, and survive the experience long enough to be in Strange. And Loki, as you said, is one of the few exceptions to your villain complaints so you've got that too.